Pyrometer background elimination

ABSTRACT

Embodiments disclosed herein provide an RTP system for processing a substrate. An RTP chamber has a radiation source configured to deliver radiation to a substrate disposed within a processing volume. One or more pyrometers are coupled to the chamber body opposite the radiation source. In one example, the radiation source is disposed below the substrate and the pyrometers are disposed above the substrate. In another example, the radiation source is disposed above the substrate and the pyrometers are disposed below the substrate. The substrate may be supported in varying manners configured to reduce physical contact between the substrate support and the substrate. An edge ring and shield are disposed within the processing volume and are configured to reduce or eliminate background radiation from interfering with the pyrometers. Additionally, an absorbing surface may be coupled to the chamber body to further reduce background radiation interference.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/522,858, filed Oct. 24, 2014, which claims benefit of U.S.Provisional Patent Application No. 61/903,079, filed Nov. 12, 2013, bothof which are hereby incorporated by reference in their entirety.

BACKGROUND

Field

Embodiments described herein generally relate to thermal processing ofsubstrates. More specifically, embodiments provided herein relate to anapparatus for pyrometer background elimination.

Description of the Related Art

A number of applications involve thermal processing of semiconductor andother materials, which require precise measurement and control of thetemperature of the materials being thermally processed. For instance,processing of a semiconductor substrate requires precise measurement andcontrol of the temperature over a wide range of temperatures. Oneexample of such processing is rapid thermal processing (RTP), which isused for a number of fabrication processes, including rapid thermalannealing (RTA), rapid thermal cleaning (RTC), rapid thermal chemicalvapor deposition (RTCVD), rapid thermal oxidation (RTO), and rapidthermal nitridation (RTN).

Temperature uniformity across the surface of the substrate is importantfor thermal processing. For example, it is desirable to have temperaturevariations of less than about 3° across the surface of the substrate toimprove thermal processing results. Conventional substrate supports thatsupport a substrate in RTP processes generally contact the substratearound the circumference of the substrate. The contact between thesubstrate support and the substrate can create temperaturenon-uniformities near the edge of the substrate. To overcome thetemperature non-uniformities associated with the physical contactbetween the substrate support and the substrate, various other methodswhich minimize contact between the support and the substrate may beutilized. However, these methods allow for excess background radiationto propagate beyond the substrate. The excess radiation may interferewith temperature metrology devices and skew temperature measurements ofthe substrate.

Thus, what is needed in the art are apparatuses for supporting asubstrate with minimal physical contact and for reducing or eliminatingbackground radiation to improve temperature measurement of an RTPsystem.

SUMMARY

In one embodiment, an apparatus for reducing background radiation isprovided. The apparatus includes a chamber body defining a processingvolume and a radiation source may be coupled to the chamber body. One ormore pyrometers may be coupled to the chamber body opposite theradiation source. A support ring may be disposed within the processingvolume and an edge ring may be disposed on the support ring. A radiationshield may be disposed above the edge ring and an inner diameter of theradiation shield may extend radially inward over a substrate supportmember of the edge ring.

In another embodiment, an apparatus for reducing background radiation isprovided. The apparatus includes a chamber body defining a processingvolume and a radiation source may be coupled to the chamber body. Awindow may separate the processing volume from the radiation source andthe radiation source may be coupled to the chamber body below thewindow. One or more pyrometers may be coupled to the chamber bodyopposite the radiation source. A support ring may be disposed within theprocessing volume and an edge ring may be disposed on the support ring.A radiation shield may be disposed above the edge ring and an innerdiameter of the radiation shield may extend radially inward over asubstrate support member of the edge ring. An absorptive coating may bedisposed on the chamber body adjacent a region where the pyrometers arecoupled to the chamber body and the absorptive coating comprises adielectric material selected to absorb or reflect radiation within adesired wavelength.

In yet another embodiment, an apparatus for reducing backgroundradiation is provided. The apparatus comprises a chamber body defining aprocessing volume and a radiation source coupled to the chamber body. Awindow may separate the processing volume from the radiation source andthe radiation source may be coupled to the chamber body above thewindow. One or more pyrometers may be coupled to the chamber bodyopposite the radiation source. A support ring may be disposed within theprocessing volume and an edge ring may be disposed on the support ring.An absorptive coating may be disposed on a bottom of the chamber bodyadjacent a region where the pyrometers are coupled to the chamber body.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 schematically illustrates a thermal processing chamber.

FIG. 2 illustrates a schematic, cross-sectional view of a thermalprocessing chamber having a radiation shield and absorbing surfacedisposed therein.

FIG. 3 is a schematic, plan view of FIG. 2 illustrating a substrate andlift pins with the radiation shield removed.

FIG. 4A is a partial, schematic cross-sectional view of the thermalprocessing chamber illustrating background radiation propagation paths.

FIG. 4B illustrates a partial, schematic cross-sectional view of thethermal processing chamber of FIG. 2.

FIG. 5 illustrates a schematic, cross-sectional view of a thermalprocessing chamber having a radiation shield and absorbing surfacedisposed therein.

FIG. 6 illustrates a partial, schematic cross-sectional view of thethermal processing chamber of FIG. 5.

FIG. 7 is a schematic, plan view of FIG. 5 illustrating a substrate andlift pins supported by an edge ring with the radiation shield removed.

FIG. 8 illustrates a partial, schematic cross-sectional view of athermal processing chamber.

FIG. 9 is a schematic, bottom view of FIG. 8 illustrating a substrateand substrate supports with a radiation shield removed.

FIG. 10 schematically illustrates a thermal processing chamber.

FIG. 11 illustrates a schematic, cross-sectional view of a thermalprocessing chamber having an edge ring and absorbing surface disposedtherein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments disclosed herein provide an RTP system for processing asubstrate. An RTP chamber has a radiation source configured to deliverradiation to a substrate disposed within a processing volume. One ormore pyrometers are coupled to the chamber body opposite the radiationsource. In one example, the radiation source is disposed below thesubstrate and the pyrometers are disposed above the substrate. Inanother example, the radiation source is disposed above the substrateand the pyrometers are disposed below the substrate. The substrate maybe supported in varying manners configured to reduce physical contactbetween the substrate support and the substrate. An edge ring and shieldare disposed within the processing volume and are configured to reduceor eliminate background radiation from interfering with the pyrometers.Additionally, an absorbing surface may be coupled to the chamber body tofurther reduce background radiation interference.

FIG. 1 schematically illustrates a processing chamber, such as theVULCAN RTP chamber available from Applied Materials, Inc. of SantaClara, Calif. A heating apparatus 124 is coupled to the chamber 100below a window 120 and is configured to heat a substrate 112 duringthermal processing. The heating apparatus comprises a plurality of lamps126, which may be separated by reflectors 127. The lamps 126 areconfigured to rapidly heat the substrate 112 to temperatures betweenabout 800° C. and about 1200° C. or greater. The reflectors 127 comprisean apparatus configured to concentrate radiation towards to thesubstrate 112. For example, the reflectors 127 may form a cavity withinwhich the lamp 126 is disposed.

The window 120, which comprises a transparent material such as quartz,separates the heating apparatus 124 from the processing region 118 ofthe chamber 100. The substrate 112 to be thermally processed issupported on its periphery by an edge ring 164. The edge ring 164 issupported by and coupled to a support ring 130. The edge ring 164 isformed from a material, such as silicon carbide or the like, capable ofwithstanding the elevated temperatures associated with thermalprocessing. Although not shown, lift pins extend through the heatingapparatus 124 and the window 120 to lift the substrate 112 off of theedge ring 164 during transfer of the substrate 112 into and out of thechamber 100. During processing, the lift pins are retracted below theedge ring 164 out of contact with the substrate 112.

A magnetic levitation system 105 is also provided. The magneticlevitation system is configured to rotate the support ring 130, edgering 164, and substrate 112 during processing. For example, the magneticlevitation system raises the support ring 130 and edge ring 164, whichis supporting the substrate 112, above the window 120 and causes theraised components to rotate around a central axis 134. In certainembodiments, the support ring 130 may be disposed radially outside thewindow 120.

One or more pyrometers 140 are coupled to the chamber 100 through achamber ceiling 128. One or more radiation collecting apparatuses 142,such as light pipes, extend through the ceiling 128 and are directedtoward the substrate 112 to measure a temperature of the substrate 112.The radiation collecting apparatuses 142 are coupled to the pyrometers140, which are further coupled to a controller 144. The controller 144receives outputs of the pyrometers 140 and accordingly controls thevoltages supplied to the heating apparatus 124. The pyrometers 140generally measure light intensity in a narrow wavelength bandwidth ofabout 30 or 40 nm in a range between about 700 nm to about 1000 nm. Thecontroller 144 converts the light intensity to a temperature through thePlank distribution of the spectral distribution of light intensityradiating from a black body held at that temperature. In this manner,temperature of the substrate 112 can be monitored during thermalprocessing.

FIG. 2 is a schematic cross-sectional view of a thermal processingchamber 200 having a radiation shield 202 and absorbing surface 250disposed therein according to one embodiment. The radiation shield 202rests on a support ring 230 as described above with regard to FIG. 1 andthe radiation shield 264 is configured to support the substrate 112. Aplurality of protrusions 208 extend from a portion 265 of the edge ring264 which is disposed below the substrate 112. For example, three orfour protrusions 208, such as pins or posts, contact and support thesubstrate 112 at discrete locations on a bottom surface of the substrate112. It is believed that the minimal physical contact between thesubstrate 112 and the protrusions 208 reduce thermal discontinuityacross the surface of the substrate 112 when compared to traditionaledge rings which support the substrate 112 around the entirecircumference of the substrate 112. The protrusions 208 substantiallyprevent the edge ring 264 from acting as a heat sink which negativelyaffects temperature uniformity of the substrate 112 during thermalprocessing.

The edge ring 264 is made from a material which is substantially opaqueand thus prevents the transmission of light through the edge ring 264.However, because the protrusions 208 separate the substrate 112 from theedge ring 264, light may propagate through the space between thesubstrate 112 and the edge ring 264 towards one or more pyrometers 240.This stray radiation, or background radiation, adversely affects thetemperature measurement of the pyrometers 240 which are configured tomeasure the temperature of the substrate 112.

To prevent or reduce background radiation, the radiation shield 202 isdisposed within the chamber 200. The radiation shield 202 issubstantially ring-like and is made of a thermally stable opaquematerial, such as silicon carbide or the like. During thermalprocessing, the radiation shield 202 is supported by the edge ring 264and at least a portion of the radiation shield 202 is disposed over atop surface of the substrate 112. The radiation shield 202 has an innerdiameter 203 which is less than a diameter of the substrate 112. Thus,the radiation shield 202 extends over and above an outer portion of thesubstrate 112.

A first plurality of lift pins 204 are configured to contact theradiation shield 202 and raise the radiation shield 202 from the edgering 264. The lift pins 204 extend through one or more voids 210 of theedge ring 164 sized to accommodate the lift pins 204. Although notshown, the lift pins 204 extend through the window 120 and the heatingapparatus 124 and are coupled to an actuator, which is configured tomove the lift pins 204 up and down along a vertical path. A secondplurality of lift pins 206 are also provided in the chamber 200. Thelift pins 206 are configured to engage the substrate 112 and support thesubstrate 112 during processing. The lift pins 206 are also configuredto raise and lower the substrate 112 to accommodate ingress and egressof the substrate from the processing volume 118.

In operation, the first plurality of lift pins 204 engage the radiationshield 202 and raise the radiation shield above and clear of a planeoccupied by the substrate 112 while the substrate 112 is beingtransferred into the chamber 200. The second plurality of lift pins 206are positioned in a raised orientation to accept the substrate 112 froma robot blade (not shown). After the substrate 112 has been engaged bythe lift pins 206, the robot blade is removed from the chamber 200 andthe lift pins 206 retract and lower the substrate 112 into a processingposition in contact with the protrusions 208. Subsequently, the liftpins 204 lower the radiation shield 202 into contact with the edge ring264 such that the radiation shield 202 rests on the edge ring 264. Thelift pins 204 then continue to retract through the voids 210 to aposition below the edge ring 264 to enable the support ring 230, edgering 264 and radiation shield 202 to be rotated by the magneticlevitation system (not shown).

A ceiling 228 of the chamber 200 has an absorbing surface 250 disposedthereon. The absorbing surface 250 is configured to absorb backgroundradiation and prevent or reduce stray background radiation from reachingthe pyrometers 240. In one embodiment, the pyrometers 240 and radiationcollecting apparatuses 242 are disposed near a center region of thechamber 200. In another embodiment, the pyrometers 240 and radiationcollecting apparatuses 242 are disposed within the chamber 200 in aregion which is above a central region of the substrate 112. Theabsorbing surface 250 may be a dielectric coating comprising variousmaterials configured to absorb radiation within a desired wavelength. Inone embodiment, the absorbing surface 250 is textured or embossed. Inaddition to absorbing stray background radiation, the topography of theabsorbing surface 250 is configured to direct background radiation awayfrom the pyrometers 240. For example, a feature of the absorbing surface250 may reflect stray background radiation not absorbed radially outwardtoward walls of the chamber 200 away from the pyrometers 240.

An interior surface 229 of the ceiling 228 radially outward of thepyrometers 240 and radiation collecting apparatuses 242 may be coatedwith the absorbing surface 250. However, portions 227 of the chamberceiling 228 between the locations where the radiation collectingapparatuses 242 extend through the ceiling 228 are not coated with theabsorbing surface 250 to prevent measurement errors of the substrate 112temperature by the pyrometers 240. The absorbing surface 250 may bedisposed over the entire interior surface 229 radially outside theportions 227 or may be disposed only on a portion of the interiorsurface 229. For example, the absorbing surface 250 may be disposed onthe interior surface 229 at locations where the majority of straybackground radiation contacts the ceiling 228.

It is believed that utilizing the radiation shield 202 in combinationwith the absorbing surface 250 may substantially reduce or eliminatestray background radiation from reaching the pyrometers. As a result,the temperature measurement of the substrate 112 by the pyrometers 240may be increased and a more accurate temperature measurement may beachieved.

FIG. 3 is a schematic plan view of FIG. 2 illustrating the substrate 112and lift pins 204 with the radiation shield 202 removed according to oneembodiment. The lift pins 204, which are configured to engage theradiation shield 202 (not shown), are disposed in a configuration suchthat the substrate 112 has an unobstructed path into and out of thechamber 200. For example, the lift pins 204 are disposed beyond an outerdiameter of the substrate 112 and outside of the path of travel(indicated by the dashed lines and arrow) of the substrate 112. In thismanner, the radiation shield 202 is raised above the plane of travel ofthe substrate 112 and the substrate 112 can be positioned by the robotblade (not shown) where the substrate 112 is engaged by the lift pins206 (not shown).

FIG. 4A is a partial schematic cross-sectional view of the thermalprocessing chamber 100 of FIG. 2 according to one embodiment. Straybackground radiation from the heating apparatus 124 propagating aroundthe edge of the substrate 112 and toward the pyrometers 240 maypropagate along various propagation paths 475. As illustrated, thepropagation paths 475 may reflect from the backside of the substrate112, the edge ring 264, the radiation shield 202, and the absorbingsurface 250. Thus, the background radiation propagation paths 475 arealtered by the presence and location of the radiation shield 202 and theabsorbing surface 250.

For example, radiation traveling along the propagation path A may beabsorbed by the absorbing surface 250 or reflected away from thepyrometers 240. Any radiation not absorbed or reflected away from thepyrometers 240 by the absorbing surface 250 travels along propagationpath B. Along this path, the radiation is directed back towards a topsurface of the substrate 112 and may then reflect upward to thepyrometers 240. Assuming the pyrometers 140 incorporate an opticalsystem to reduce the field of view and the minimal view angle 490 of thepyrometers 240 to the substrate 112 is less than between about 25° andabout 50°, such as less than about 30°, stray background radiationmeasured by the pyrometers 240 may be substantially reduced.

FIG. 4B is a partial schematic cross-sectional view of the thermalprocessing chamber 100 of FIG. 2 according to one embodiment. Aspreviously discussed, the background radiation propagation paths arealtered by the radiation shield 202 and the absorbing surface 250 toreduce the incidence of background radiation from being detected by thepyrometers 240. The relationships between the various components of thechamber 200 are generally responsible for determining the propagationpaths of the background radiation.

In one embodiment, the radiation shield 202 extends laterally inwardover an edge of the substrate 112 a first distance 406. A seconddistance 404, measured from an inner surface 201 of the radiation shield202 to a location on the ceiling 228 where the radiation collectingapparatus 242 is disposed, is greater than the first distance 406. Theabsorbing surface 250 may be disposed over a portion of or over theentire distance 404 on the interior surface 229 of the ceiling 228. Inanother embodiment, the radiation shield 202 is disposed a thirddistance 402 above the substrate 112. A fourth distance 408, measuredfrom the interior surface 229 of the ceiling 228 to the substrate 112 ina processing position, is greater than the third distance 402. Thespatial relationships between the radiation shield 202, ceiling 228,radiation collecting apparatuses 242 and pyrometers 240, and thesubstrate 112 provide for the reduction or elimination of straybackground radiation being measured by the pyrometers 240.

FIG. 5 is a schematic cross-sectional view of a thermal processingchamber 200 having a radiation shield 504 and absorbing surface 250disposed therein according to one embodiment. The chamber 200 andcomponents disposed therein are substantially similar to the chamber 200and components described with regard to FIG. 2. However, the radiationshield 504 is coupled to and supported by a third plurality of lift pins502. The lift pins 502 are configured and function similarly to the liftpins 204 described with regard to FIGS. 2 and 3, but in this embodiment,the lift pins are 502 disposed radially outward of the support ring 230and an edge ring 564. The radiation shield 202 extends from the liftpins 502 radially inward over the substrate 112 such that the innerdiameter 203 of the radiation shield 202 is the same as the innerdiameter 203 described with regard to FIG. 2.

FIG. 6 is a partial schematic cross-sectional view of the thermalprocessing chamber 200 of FIG. 5 according to one embodiment. Thedistances 402, 404, 406 and 408 are similar to and described in greaterdetail with regard to FIG. 4B. Here, the lift pins 502 are not disposedthrough the edge ring 564, which reduces the complexity of manufacturingthe edge ring 564 and the necessity of the lift pins 204 to extendthrough the edge ring 564. For example, the edge ring 564 does not havevoids formed therethrough to allow for passage of lift pins, whichallows the edge ring 564 to more effectively prevent the propagation ofbackground radiation from reaching the substrate 112.

FIG. 7 is a schematic plan view of FIG. 5 illustrating the substrate 112supported by the edge ring 564 and the lift pins 502 with the radiationshield 504 removed according to one embodiment. As illustrated, thesubstrate 112 is supported by the protrusions 208 (not shown) of theedge ring 564. The lift pins 502, which are configured to engage theradiation shield 504 (not shown), are disposed in a configuration suchthat the substrate 112 has an unobstructed path into and out of thechamber 200. For example, the lift pins 502 are disposed beyond an outerdiameter of the edge ring 564 and outside of the path of travel(indicated by the dashed lines and arrow) of the substrate 112. In thismanner, the radiation shield 504 is raised above the plane of travel ofthe substrate 112 and the substrate 112 can be positioned by the robotblade (not shown) where the substrate 112 is engaged by the lift pins206 (not shown). In this embodiment, the lift pins 502 are disposedradially outward of the edge ring 564.

FIG. 8 is a partial schematic cross-sectional view of the thermalprocessing chamber 200 according to one embodiment. In this embodiment,supports 802 of the radiation shield 202 support the substrate 112instead of an edge ring 864. The edge ring 864, which is supported bythe support ring 230, supports the radiation shield 202. The supports802 are coupled to the radiation shield 202 and extend below theradiation shield 202. The supports 802 comprise a first member 804 whichextends downward from the radiation shield 202, a second member 806which extends substantially horizontally from the first member 804, andone or more protrusions 808. The supports 802 may be a separateapparatus coupled to the radiation shield 202 or may be an integral partof a unitary body with the radiation shield 202. The supports 802 maycomprise the same material as the radiation shield 202, which is amaterial capable of withstanding thermal processing conditions, such assilicon carbide. In one embodiment, the supports 802 may be atransparent material, such as quartz, which may prevent shadowing ofradiation from the heating apparatus 124 to prevent cold spots fromforming on the substrate 112 during processing.

In one embodiment, three supports 802 may be utilized to support thesubstrate 112. The first member 804 extends from the radiation shield202 from a location radially outwards from the circumference of thesubstrate 112 when the substrate is located in the processing position.The second member 806 extends from the first member 804 such that atleast a portion of the second member 806 is disposed beneath thesubstrate 112 when the substrate 112 is in a processing position. Theprotrusions 808 extend from the second member 806 and contact thesubstrate 112. In this example, only the protrusions 808 contact thesubstrate 112 so as to minimize physical contact between the substrate112 and the supports 802.

The first plurality of lift pins 204 function as described with regardto FIG. 2. By utilizing the supports 802, no lift pins to support thesubstrate 112 are necessary as the supports 802 are coupled to theradiation shield 202. It is contemplated that the spacing andrelationship between the first member 804, second member 806, andprotrusions 808 are configured to allow for a robot blade to place andretrieve the substrate 112 without utilizing any additional apparatusesfor separating the substrate 112 from the protrusions 808. Thus, no liftpins for the substrate 112 are necessary which reduces the complexity ofthe chamber 200. Further, the distances 402, 404, 406 and 408 aresimilar to those described with regard to FIGS. 4B and 6 although themanner of supporting the substrate 112 is different.

FIG. 9 is a schematic bottom view of the embodiments shown in FIG. 8illustrating the substrate 112 and supports 802 with a radiation shield202 removed according to one embodiment. As illustrated, the substrate112 is supported by the supports 802. The first member 804 extendsvertically (into the page) and the second member 806 extendshorizontally from the first member 804. The first member of each support802 is disposed beyond the path of travel (indicated by the dashed linesand arrow) of the substrate 112. The second member 806 of each of thesupports 802 extends to a position inside the diameter of the substrate112 to allow the substrate 112 to rest on the protrusions 808 (notshown) extending from the second member 806. The substrate 112 travelsabove the second member 806 and is lowered onto the protrusions 808 ofthe second member 806 by the robot blade which is then retracted alongthe substrate 112 travel path. Although not shown, the radiation shield202 is spaced a distance from the second member 806 configured such thatthe robot blade and substrate 112 are unobstructed while positioning andmoving the substrate 112.

FIG. 10 schematically illustrates a processing chamber 1100, such as theRADIANCE® RTP chamber available from Applied Materials, Inc. of SantaClara, Calif. A heating apparatus 124 is coupled to the chamber 1100above a window 120 and is configured to heat a substrate 112 duringthermal processing. The heating apparatus 124 comprises a plurality oflamps 126, which may be separated by reflectors 127. The lamps 126 areconfigured to rapidly heat the substrate 112 to temperatures betweenabout 800° C. and about 1200° C. or greater. The reflectors 127 comprisean apparatus configured to concentrate radiation towards to thesubstrate 112. For example, the reflectors 127 may form a cavity withinwhich the lamp 126 is disposed.

The window 120, which comprises a transparent material such as quartz,separates the heating apparatus 124 from the processing region 118 ofthe chamber 1100. The substrate 112 to be thermally processed issupported on its periphery by an edge ring 1064. The edge ring 1064 issupported by and coupled to a support ring 1030. The edge ring 1064 isformed from a material, such as silicon carbide or the like, capable ofwithstanding the elevated temperatures associated with thermalprocessing. Although not shown, lift pins extend through a bottom 1017of the chamber 1100 to lift the substrate 112 off of the edge ring 1064during transfer of the substrate 112 into and out of the chamber 1100.During processing, the lift pins are retracted below the edge ring 1064out of contact with the substrate 112.

A magnetic levitation system 105 is also provided. The magneticlevitation system 105 is configured to rotate the support ring 1030,edge ring 1064, and substrate 112 during processing. For example, themagnetic levitation system 105 raises the support ring 1030 and edgering 1064, which is supporting the substrate 112, within the processingvolume 118 and causes the raised components to rotate around a centralaxis 134. In certain embodiments, the support ring 1030 may be disposedradially outside the window 120.

One or more pyrometers 1040 are coupled to the chamber 1100 through thechamber bottom 1017. One or more radiation collecting apparatuses 1042,such as light pipes, extend through the chamber bottom 1017 and aredirected toward the substrate 112 to measure a temperature of thesubstrate 112. The radiation collecting apparatuses 1042 are coupled tothe pyrometers 1040, which are further coupled to a controller 1044. Thecontroller 1044 receives outputs of the pyrometers 1040 and accordinglycontrols the voltages supplied to the heating apparatus 124. Thepyrometers 1040 generally measure light intensity in a narrow wavelengthbandwidth of about 30 or 40 nm in a range between about 700 nm to about1000 nm. The controller 1044 converts the light intensity to atemperature through the Plank distribution of the spectral distributionof light intensity radiating from a black body held at that temperature.In this manner, temperature of the substrate 112 can be monitored duringthermal processing.

FIG. 11 is a schematic cross-sectional view of the thermal processingchamber 1110 having the edge ring 1164 and absorbing surface 250disposed therein according to one embodiment. The edge ring 1164 restson the support ring 1130 as described above and the edge ring 1164 isconfigured to support the substrate 112. The plurality of protrusions208 extend from the portion 1165 of the edge ring 1164 which is disposedbelow the substrate 112. For example, three or four protrusions 208,such as pins or posts, contact and support the substrate 112 at discretelocations on a bottom surface of the substrate 112. It is believed thatthe minimal physical contact between the substrate 112 and theprotrusions 208 reduce thermal discontinuity across the surface of thesubstrate 112 when compared to traditional edge rings which support thesubstrate 112 around the entire circumference of the substrate 112. Theprotrusions 208 substantially prevent the edge ring 1164 from acting asa heat sink, which negatively affects temperature uniformity of thesubstrate 112 during thermal processing.

The edge ring 1164 is made from a material which is substantially opaqueand thus prevents the transmission of light through the edge ring 1164.However, because the protrusions 208 separate the substrate 112 from theedge ring 1164, light may propagate through the space between thesubstrate 112 and the edge ring 1164 towards the pyrometers 1140. Thisstray radiation, or background radiation, adversely affects thetemperature measurement of the pyrometers which are configured tomeasure the temperature of the substrate 112.

A plurality of lift pins 206 are provided in the chamber 1110. The liftpins 206 are configured to engage the substrate 112 and support thesubstrate 112 during processing. The lift pins 206 are also configuredto raise and lower the substrate 112 to accommodate ingress and egressof the substrate 112 from a processing position. In operation, theplurality of lift pins 206 are positioned in a raised orientation toaccept the substrate 112 from a robot blade (not shown). After thesubstrate 112 has been engaged by the lift pins 206, the robot blade isremoved from the chamber 110 and the lift pins 206 retract and lower thesubstrate 112 into a processing position in contact with the protrusions208. The lift pins 206 retract further to a position out of contact withthe substrate 112 to enable the support 1130 and edge ring 1164 to berotated by the magnetic levitation system (not shown).

The bottom 1117 of the chamber 1110 has the absorbing surface 250disposed thereon. The absorbing surface 250 is configured to absorbbackground radiation and prevent or reduce stray background radiationfrom reaching the pyrometers 1140. The absorbing surface 250 may be adielectric coating comprising various materials configured to absorbradiation within a desired wavelength. In one embodiment, the absorbingsurface 250 is textured or embossed. In addition to absorbing straybackground radiation, the topography of the absorbing surface 250 isconfigured to direct background radiation away from the pyrometers 1140.For example, a feature formed by roughening or embossing the absorbingsurface 250 may reflect stray background radiation not absorbed radiallyoutward toward the support ring 1130 away from the pyrometers 1140.

An interior surface 1151 of the bottom 1117, disposed radially outwardof the pyrometers 1140 and radiation collecting apparatuses 1142, may becoated with the absorbing surface 250. However, portions 1153 of thechamber bottom 1117 between the locations where the radiation collectingapparatuses 1142 extend through the chamber bottom 1117 are not coatedwith the absorbing surface 250 to prevent measurement errors of thesubstrate 112 temperature by the pyrometers 1140. The absorbing surface250 may be disposed over the entire interior surface 1151 radiallyoutside the portions 1153 or may be disposed only on a portion of theinterior surface 1151. For example, the absorbing surface 250 may bedisposed on the interior surface 1151 at locations where the majority ofstray background radiation contacts the bottom 1117.

It is believed that utilizing the absorbing surface 250 maysubstantially reduce or eliminate stray background radiation fromreaching the pyrometers 1140. As a result, the temperature measurementof the substrate 112 by the pyrometers 1140 may be increased and a moreaccurate temperature measurement may be achieved.

Embodiments described herein utilize a radiation shield and absorbingsurface, either alone or in combination to reduce the negative effectsof stray background radiation on pyrometer temperature measurement.Methods of supporting the substrate to reduce heat discontinuity acrossthe surface of the substrate are utilized in concert with the radiationshield and absorbing surface. As a result, accuracy of substratetemperature measurement by the pyrometers can be improved by removingthe interfering background radiation. Embodiments described herein maybe utilized on chambers which incorporate heating apparatuses eitherabove or below the substrate. For example, embodiments described hereinmay be especially useful in the RADIANCE® and VULCAN processing chambersavailable from Applied Materials, Inc., Santa Clara, Calif. However, itis contemplated that the embodiments described herein may alsoadvantageously be incorporated on processing chambers from othermanufacturers.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

The invention claimed is:
 1. An apparatus for processing a substrate,comprising: a chamber having a window and a ceiling at least partiallydefining a process volume; a radiation source disposed adjacent to thewindow; one or more pyrometers coupled to the ceiling opposite theradiation source; a support ring disposed within the processing volume;an edge ring having a substrate support portion, the edge ring coupledto the support ring; and a radiation shield removably coupled to theedge ring, wherein an inner diameter of the radiation shield extendsradially inward over the substrate support portion of the edge ring andabove a top most surface of the edge ring, and wherein the innerdiameter of the radiation shield is less than an inner diameter of thesubstrate support portion of the edge ring.
 2. The apparatus of claim 1,further comprising: an absorbing surface disposed on the ceilingadjacent to a region where the one or more pyrometers are coupled to theceiling.
 3. The apparatus of claim 1, wherein the window separates theprocess volume from the radiation source.
 4. The apparatus of claim 3,wherein window is a quartz material.
 5. The apparatus of claim 1,wherein the edge ring and the radiation shield comprise a ceramicmaterial.
 6. The apparatus of claim 1, wherein the edge ring furthercomprises: a plurality of discrete protrusions extending from an uppersurface of the substrate support portion of the edge ring.
 7. Theapparatus of claim 1, wherein the edge ring further comprises: aplurality of voids formed therein and sized to allow passage of liftpins therethrough.
 8. The apparatus of claim 2, wherein the one or morepyrometers are coupled to the ceiling via one or more radiationcollecting apparatuses.
 9. The apparatus of claim 2, wherein theabsorbing surface is a dielectric material.
 10. The apparatus of claim2, wherein the absorbing surface is textured.
 11. The apparatus of claim8, wherein the radiation collecting apparatuses are coupled to a centralregion of the ceiling.
 12. The apparatus of claim 1, wherein theradiation shield further comprises: a plurality of supports extendingtherefrom.
 13. The apparatus of claim 12, wherein the plurality ofsupports are coupled to a bottom surface of the radiation shield, thesupports comprising a first member, a second member, and a supportmember.
 14. The apparatus of claim 13, wherein the first member extendsvertically from the radiation shield, the second member extendshorizontally from the first member, and the support member extendsvertically from the second member.
 15. An apparatus for processing asubstrate, comprising: a chamber having a window and a ceiling at leastpartially defining a process volume; a radiation source disposedadjacent to the window; one or more pyrometers coupled to the ceilingopposite the radiation source; a support ring disposed within theprocessing volume; an edge ring having a substrate support portion, theedge ring coupled to the support ring; a plurality of lift pins moveablydisposed in the process volume radially outward from the support ring;and a radiation shield coupled to the plurality of lift pins, wherein aninner diameter of the radiation shield extends radially inward over thesubstrate support portion of the edge ring and above a top most surfaceof the edge ring, and wherein the inner diameter of the radiation shieldis less than an inner diameter of the substrate support portion of theedge ring.
 16. The apparatus of claim 15, further comprising: anabsorbing surface disposed on the ceiling adjacent to a region where theone or more pyrometers are coupled to the ceiling.
 17. The apparatus ofclaim 16, wherein the absorbing surface has a topology which directsradiation away from the one or more pyrometers.
 18. The apparatus ofclaim 17, wherein the absorbing surface is a dielectric material havinga textured surface.
 19. An apparatus for processing a substrate,comprising: a chamber having a window and a ceiling at least partiallydefining a process volume; a radiation source disposed adjacent to thewindow; one or more pyrometers coupled to the ceiling opposite theradiation source; a support ring disposed within the processing volume;an edge ring coupled to the support ring; a plurality of lift pinsmoveably disposed in the process volume radially inward from the supportring and the edge ring; a radiation shield removably coupled to theplurality of lift pins and the edge ring; and a plurality of supportsextending from a bottom surface of the radiation shield, wherein theplurality of lift pins are positioned to contact the radiation shieldbetween the edge ring and the plurality of supports.
 20. The apparatusof claim 19, further comprising: a dielectric material absorbingsurface, having a topology which directs radiation away from the one ormore pyrometers, disposed on the ceiling adjacent to a region where theone or more pyrometers are coupled to the ceiling.